A CTV reporter in Beacon Hill said there was almost nothing left. "It's just blocks and blocks of soot, basically," she said.

A terrifying experience: Szymon Bicz, eyewitness

Image copyrightAP

"I'm on the road to Edmonton, after managing to escape Fort McMurray in a hurry. It's chaos here. Everyone has been advised to evacuate immediately. The roads are gridlocked.

The smoke was really overpowering. It was a terrifying experience. I was at work listening to the radio for updates, where they were saying it was contained initially.

Then it spread really rapidly. I drove back to my house and grabbed my passport and some clothes and started driving out of town with a colleague. My family have not moved over yet from the UK.

The thick black smoke was closing in and surrounded the car. People were driving up on paths and grass verges just to get out of there. I'm hoping my rented house is still intact but I just don't know.

The whole region is at risk. It's absolutely catastrophic, but people here are big-hearted. Volunteers on the highway to Edmonton are giving food and water as required."

Ms Notley praised Albertans for helping neighbours in need.

"We will get through this and we will come out stronger on the other side," she said.

Unseasonably high temperatures and strong winds have combined with dry conditions to leave much of Alberta and neighbouring Saskatchewan under an extreme fire risk warning.

Prime Minister Justin Trudeau said he would send military aircraft to help if they were needed.

Image copyright@JustinTrudeau

Fort McMurray is a major centre of Canada's oil sands industry - with vast oil reserves - and a major evacuation of staff was ordered.

Suncor Energy said its main plant was so far safe but crude production was being cut.

Shell Canada said it was opening its camp to evacuees.

Canada Post has suspended all deliveries to Fort McMurray.

Fort McMurray: Canada's 'manliest' city

On its tourism website, Fort McMurray describes itself as the "gateway to the north" - a region which is home to the third largest reserves of oil in the world behind Saudi Arabia and Venezuela.

It may be remote, but Fort McMurray's proximity to Canada's rich oil sands has helped it to become a hugely prosperous place, drawing oil workers from across the world.

It is not strictly speaking a city, but such has become Fort McMurray's importance in the region that it is commonly referred to as one.

Canada's National Post called Fort McMurray "Canada's manliest city" where men outnumber women by roughly three to two.